Abstract: A device for regulating a motor-driven foldable rear view mirror of an automobile is disclosed. The device has a shaft reinforcing ring having a plurality of U-shaped slots on its upper outside edge, and a frame reinforcing ring having a plurality of V-shaped slots on its upper inside edge. The frame reinforcing ring is placed about the shaft reinforcing ring, so that their slots are opposed to each other respectively. A plurality of regulating balls are seated on the slots of the reinforcing rings and placed in guide depressions of a shaft gear, so that the balls can move radially of the shaft. The reinforcing rings are tightly compressed by a compression coil spring and tightly kept in their places during the operation of the device.